Answer:
it's aphelion distance is 18.41 AU
Step-by-step explanation:
Given data:
eccentricity 0.87
P is period of orbiting = 79
from Kepler's third Law.
P^2 = d^3
where P is the period of orbiting in years, and
d it is orbit semi-major axis in Astronomical Units
1 AU is the average distance between earth and sun
so if P =79, we have
79^2 = d^3
6241 = d^3
d = (6241)^(1/3) = 18.41 AU